Research conducted on mice by the University of Edinburgh indicates that low levels of male hormones, known as androgens, “at the equivalent to 8–12 weeks human gestation” may result in disorders such as low sperm count and testicular cancer, reports the BBC.

The head of the study, Dr. Michelle Welsh, was surprised that the low androgen levels made such a difference that early on in pregnancy.

According to Professor Richard Sharpe, co-author of the study, one in five young men suffer from a sperm count that could make it hard for them to conceive.

The findings comes on the heels of other recent studies related to fertility, sperm count and genetics.

The results of a University of Idaho study appeared in February, calling attention to the effect of a father’s health on his children. The study found that certain sperm defects, perhaps caused by smoking or drinking, might be passed down to future generations.

“In experiments on rats Matthew Anway of the University of Idaho found that some garden chemicals caused problems such as damaged and overgrown prostates, infertility and kidney problems, all of which were present up to four generations later,” according to The Guardian.

In addition, on March 7 the Italian publication Corriere Della Sera reported on research citing a drastic fall in the active sperm counts of Italian men. Active Italian sperm counts have halved since the 1970s, according to the study. The count is lower in larger cities than smaller towns and villages, possibly owing to environmental factors.

On March 17, 2008, the BBC reported that recent research found that “common genital disorders, low sperm count and testicular cancer could all be linked to hormone levels early in pregnancy.” The study also “found that the level of androgen hormone at this time was related to the distance between the base of the penis and the anus.”

A recent University of Idaho in Moscow study has indicated that “sperm defects caused by exposure to environmental toxins can be passed down the generations,” reports the BBC. Garden chemicals causing sperm defects in one generation of rats could remain “up to four generations later.” The finding raises concerns that smoking or drinking may affect the DNA of a man’s sperm to the degree that defects can be passed to future generations.

In reference to the University of Idaho study, Cynthia Daniels of Rutgers University said, “Historically it has been assumed that exposures to the male will not affect his ability to pass defects on to children," quotes The Guardian. The recent study, however, calls that idea into question by suggesting that a father’s health, like a mother’s, can influence the health of a child. “Vietnam veterans exposed to agent orange, for example, have been shown to have children with increased rates of spina bifida."

A recent study found that the active sperm count of Italian men has dropped by half since the 1970s. Furthermore, environmental factors may play a large part in the results. “Men who reside in bigger cities or agricultural locations where the use of pesticides is common had 20 percent less mobile sperm than smaller town and village dwellers," findingDulcinea reported on March 15, 2008.

A 2006 article from Slate presents a theory explaining the falling rates of teen pregnancy since 1990. What if there is an explanation “that has nothing to do with just-say-no campaigns or safe-sex educational posters? What if teenagers are less fertile than they used to be? Not the girls—the boys?” Many studies have indicated that environmental factors are the main culprits. “There is no government-sponsored effort to track male fertility rates, even though male-factor problems account for half of all infertility.”